[BUILD] 1176LN Rev D DIY

[strangeandbouncy]

Thank you very much indeed. Ed, for that explaination. I hadn't considered either stray field or voltage droop.


I shall look for 30-0-30v at 25VA


Thanks,

ANdyP

 

[enthalpystudios]

.....hmm... what to do with 30 160hfe 2n3707's?

**** ;]

 

[Sleeper]

add 25 more low hfe 3707s here.
besides another fuzz face?
hmmm.
another fuzz face it is.
Kelly

 

[JdJ]

Just curious,

Are you guys checking the 3707s in the circuit, or with a tester? I'm wondering if I should socket mine for testing in the circuit as I am hesitant to buy a dedicated tester. Is there even a socket that will fit the footprint on the board?

Cheers,

Josh

 

[Sleeper]

tested in the hfe tester of my DMM.
not sure how to test HFE with a circuit, but I'm sure someone around here does. You might try the meta. sorry I couldn't be more help.
still waiting for replacement transistors.
as for the socket you can always cut apart a sipp socket (in line header- like the kind you'll need for the THAT vca chips) but- if you put the low hfe transistors in there I've got no idea if the circuit would not work or if it would just work but poorly- this could be very difficult to troubleshoot.

Kelly

 

[JdJ]

Testing in the circuit seems to be the only other way to do it, unless you build a jig that replicates the circuit (which seems kind of redundant to me). I think essentially you are measuring the forward voltage with a set control bias present (via signal generator) or something like that.

[edit] took out needless confusing and possibly incorrect info[/edit]

There are a few threads about it around here, but I was just curious how people were doing it.

Time to go DMM shopping?!

Thanks,

Josh

 

[nerd]

edanderson - I don't know if you are using this thread for a count on output transformers, but if you are, please count me in for two.


What are the rest of you guys going with for input transformers? Are you trying to source the UTC o-12s? There are two on ebay now for $200. That seems pricey. (or is it, I don't know?) There was talk of the altran copy (C-3837-1) earlier in this thread, but that idea seems to have died off.

 

[Sleeper]

the 0-12 input transformers are wired 500 to 250 ohm and I think they are rated at +8dbm
pretty much any good 600 to 600/300 transformer should be great.
for example, you can find utc a21s for much less money.
I used some triads on my g1176 and they sound verry nice.
have 2 more for this one. I'll bet edcors would work fine.
The mounting is offboard so there aren't any footprint worries.
go nuts.

got my 2n3708s today. all tested out around 300hfe.
onward!

Kelly

 

[edanderson]

[quote author="nerd"]edanderson - I don't know if you are using this thread for a count on output transformers, but if you are, please count me in for two. [/quote]

i'm not using this thread to keep track. i should have some output transformers in about a week. look for an ad in the black market.

[quote author="nerd"]Are you trying to source the UTC o-12s? There are two on ebay now for $200. That seems pricey. (or is it, I don't know?) There was talk of the altran [utc o-12] copy (C-3837-1) earlier in this thread, but that idea seems to have died off.[/quote]

$100ea for an o-12 is quite excessive. $25ea is more like it, but i guess whatever people will pay.

the escalating prices on o-12s is why purple started using the altran part, which we had done as a custom part. the problem with using the altran part for the mnats board is that it is PCB mount, and there is no place for it on the board. i haven't found any can clamps that would work very well, so mounting would have to be on a piece of perf board. the pin spacing is 0.15", different from most perf which is 0.1" so even that will be a pain. i suppose someone could make up an input PCB, with pads for various input transformers, input attenuators, etc.

if there is any interest in the altran o-12, i can put together an order, but so far i havent seen the need.

ed

 

[mnats]

There were a few reasons I didn't want to mount the input transformer on-board. One is that I was unsure what people wanted to use there and thought it would be best to wait until some options had been explored. Another was that presumably a fixed position would limit the mounting options for the board in relation to the power transformer especially for dual/stereo configurations. The main reason, however, was that my board design was done and adding a transformer footprint to it without an extensive rework would have looked like something had been tacked on as an afterthought.

My thinking at the time and now is to sort out the common transformers/input configurations that work well then make a separate board - possibly with several transformer footprints - to create a clean way of mounting the input transformer without having to worry about turning the main board this way or that to avoid interaction with the power transformer. Hope that makes sense.

When we get the input circuit sorted and have a few nice choices then I'll do a separate PCB. If everyone decides to use the original UTC well there won't be a need for a PCB at all. Personally I'm very interested in the Altran part.

 

[kazper]

I would also be in for the Altran. I don't want to pay over $100 for a transformer or buy two when I want to do just one unit.

One may be able to just hose clamp it to a couple metal supports. A custom board from a self etch may also work just fine. It may be a reason for me to actually do a self etch. I know I could think of something that would look nice without costing a arm and a leg.

Count me in on the Altran Transformer for one possibly two. It all depends on if I can source another T-pad. I definitely will grab a output transformer or two from you for this project.

BTW Mallory sells a 600 ohm T-Pad for around $100 Each new.

 

[matthias]

I will build mine with the new that 1200 line receiver ics at the input

but I've got a nother question. refering to the original revD schematic you should also match the output transistors

so what about that..??

 

[strangeandbouncy]

edanderson,

we wait like hungry cuckoos, mouths open in anticipation . . .

seriously, personally, i will be extremely greatful if you can produce a suitable transformer! I am surely not alone, - You the Man!

Kindest regards,

ANdyP

 

[shabtek]

ye-yass,

i'm interested in a few i's and o's!!!

 

[dmix]

Just use for input cinemag CMMI-2C @ $60.85 each and for output CM96731 @ $47.35 each

purchase directly from cinemag

 

[mnats]

dmix - what quantities are you quoting Cinemag prices for? My understanding was they had a minimum quantity of 5 at that price for the opt.

So you've tried the CMMI-2C on the input in this circuit? What can you tell us about how it compares sonically to the UTC ouncer?

I received my iron from Purple this week so I finished off one fabricated board to test the output circuit. It all works fine. I wouldn't suggest using anything but the Cinemag on the output. Though it 'works' with a normal output transformer or with the feedback winding removed the performance is badly compromised as you would expect.

 

[edanderson]

re: the CM96731 output, i was also told that there was a 5pc minimum order, which is why i went ahead and ordered some to sell to people with mnats boards. i will check with tom and david; if they are willing to sell single transformers to everyone, then i will get out of the way. david said they were going to ship my order this week, so i should have them pretty soon. please do not PM me; i will post an ad in the black market as soon as they are available.

as for using the cmmi-2c as an input, yeah it probably will work, but i doubt it will sound much like an O-12 (which could be a good thing in some cases!). i did suggest it back in 2005 but i think that there are better options available now.

ed

 

[tommypiper]

Hi Ed, I already went over it extensively with David some time ago; they will not sell small quantities individually. David suggested a group order for those who want small quantities. I was going to consider a group order or buy a bunch and offer the extras, but you beat me to it as I was short on credit card headroom for a while. :grin: Glad we're all moving forward.

Mako, good to hear you finally got your Purple iron and everything is working. :thumb:

I may use a Lundahl or experiment with 1:1 types for the input.

 

[thenovice]

so what is the best bet for the output then?

 

[Sleeper]

Sounds like the ONLY bet is to wait for Ed, unless you're buying 5 direct.

Kelly